Spectroscopic ellipsometric characterization of Si/Si1-xGex strained-layer supperlattices

H. Yao, J. A. Woollam, P. J. Wang, M. J. Tejwani, S. A. Alterovitz

Research output: Contribution to journalArticle

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Abstract

Spectroscopic ellipsometry (SE) was employed to characterize Si/Si1-xGex strained-layer superlattices. An algorithm was developed, using the available optical constants measured at a number of fixed x values of Ge composition, to compute the dielectric function spectrum of Si1-xGex at an arbitrary x value in the spectral range 1.7 to 5.6 eV. The ellipsometrically determined superlattice thicknesses and alloy compositional fractions were in excellent agreement with results from high-resolution X-ray diffraction studies. The silicon surfaces of the superlattices were subjected to a 9 : 1 HF cleaning prior to the SE measurements. The HF solution removed silicon oxides on the semiconductor surface, and terminated the Si surface with hydrogen-silicon bonds, which were monitored over a period of several weeks, after the HF cleaning, by SE measurements. An equivalent dielectric layer model was established to describe the hydrogen-terminated Si surface layer. The passivated Si surface remained unchanged for > 2 h, and very little surface oxidation took place even over 3 to 4 days.

Original languageEnglish (US)
Pages (from-to)52-56
Number of pages5
JournalApplied Surface Science
Volume63
Issue number1-4
DOIs
StatePublished - Jan 1993

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Spectroscopic ellipsometry
ellipsometry
cleaning
Superlattices
Silicon
superlattices
Hydrogen
Cleaning
silicon
hydrogen
silicon oxides
Optical constants
Silicon oxides
surface layers
oxidation
Semiconductor materials
high resolution
X ray diffraction
Oxidation
diffraction

ASJC Scopus subject areas

  • Surfaces, Coatings and Films

Cite this

Spectroscopic ellipsometric characterization of Si/Si1-xGex strained-layer supperlattices. / Yao, H.; Woollam, J. A.; Wang, P. J.; Tejwani, M. J.; Alterovitz, S. A.

In: Applied Surface Science, Vol. 63, No. 1-4, 01.1993, p. 52-56.

Research output: Contribution to journalArticle

Yao, H. ; Woollam, J. A. ; Wang, P. J. ; Tejwani, M. J. ; Alterovitz, S. A. / Spectroscopic ellipsometric characterization of Si/Si1-xGex strained-layer supperlattices. In: Applied Surface Science. 1993 ; Vol. 63, No. 1-4. pp. 52-56.
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